Crystal controlled circuit



Dec. 18, 1934.

H. ROTHE CRYSTAL CONTROLLED CIRCUIT Filed July 27, 1933 INVENTOR HO T OTHE BY/ ATTORNEY Patented Dec. 18, 1934 PATENT OFFICE CRYSTAL CONTROLLED CIRCUIT Horst Rothe, Berlin,

Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic 111. b. 11., Berlin, Germany, a corporation of Germany Application July 27, 1933, Serial No. 682,381 In Germany July 18, 1932 3 Claims. '(Cl. 250-36) This invention relates to a regenerative circuit scheme comprising a piezo-electric resonator.

Piezo-electric resonators have been adopted 5 so widely in actual practice of radio-frequency engineering for the stabilization of radio frequency oscillations that nothing need be said on this score. A piezo-electric resonator may. be represented by a series arrangement of capacity and inductance.

Hence, in the state of resonance, it involves a minimum of impedance. However, as far as applicant is aware, all of the circuit arrangements known in the prior art wherein piezo-electric resonators are caused to enter tubes into oscillations by the aid of electron operate in such a way that the resonator is excited at a frequency adjacent to its own or natural frequency rather than at the latter inasmuch as all of these schemes may be traced back to self-exciting schemes in which a parallel arrangement of capacity and inductance is excited. Hence, in all of these circuit arrangements the ensuing wave does not correspond to the natural period of the resonator and is a function of the working data to a rather appreciable degree. late that In fact, it has only been of electron-tube circuit arrangements have become known which possess an arc characteristic, in other words, in which a series arrangement of inductance and capacitance may be caused to enter into a state of self-oscillations.

According to the present invention, these circuit schemes are utilized for the excitation of piezo-electric resonators.

One form among a number of conceivable circuit schemes is shown in the attached drawing.

In the plate circuit of the tube 1 is included the piezo-electric resonator P in series with an ohmic resistance R1.

Plate potential is fed to the said tube by way of an ohmic resistance and a choke coil which are required for stabilizing purposes.

The voltage prevailing across the back.

If the resistances are properly proportioned, this circuit assembly will oscillate exactly at the natural period of the piezo-electric resonator. The radio frequency energy may be taken off (tapped) at the resistance R2 and be fed to additional amplifier stages. The resist- 5 ance R2 may be replaced by an oscillation circuit comprising a parallel connection of capacity and inductance. The radio frequency energy could also be derived by galvanic or other suitable coupling means. Obviously the tubes may be of the tetrode or screen grid type and may have indirectly heated cathodes. Quite apart from such an assembly comprising two tubes of thermionic type, the invention may be carried out with a system wherein one electron or thermionic tube is used, though the feature of such a scheme would also consist in the arc characteristic; in other words, a series arrangement comprising capacity and inductance is excited at its natural frequency. 0

Having thus described my invention what I claim is:

1. An oscillatory system comprising a tube having an anode and cathode and a control electrode, a serial combination of a crystal and a resistance connected between said anode and said cathode, a circuit connected between said grid and cathode, and an electron discharge device having a plate, a grid,- and a filament for feeding back energy from said anode and cathode circuit to said grid cathode circuit, the grid and filament of said device being connected to said resistance and the plate and filament being coupled to the control electrode and cathode of said tube. 35

2. In combination, a multi-electrode device having an anode, a cathode, and a control electrode, a two electrode crystal in series with a resistance connected between said anode and cathode, a tube having a plate, a grid and. a filament, means connecting said grid and filament to said resistance, an impedance, and means coupling said plate and filament and said control electrode and cathode to said impedance.

3. Apparatus as claimed in the preceding 45 claim, characterized by the fact that said impedance is in the form, of a resistance.

HORST ROTHE. 

